Wobble plate pump



July 4, 1961 R. M. TUCK ETAL 2,990,781

WOBBLE PLATE PUMP Filed Nov. 25, 1957 3 Sheets-Sheet 1 IN VEN TORS 5y Ip ATTORNEY w July 4, 1961 R. M. TUCK ETAL 2,990,781

WOBBLE PLATE PUMP Filed Nov. 25, 1957 3 Sheets-Sheet 2 IN VEN TORS July4, 1961 R. M. TUCK ETAL WOBBLE PLATE PUMP Filed Nov. 25, 1957 5Sheets-Sheet 3 rrow/gr United States Patent s 2,990,781 iatented July 4,1961 2,990,781 WOBBLE PLATE PUMP Robert M. Tuck and James J. Mooney, In,Indianapblis, lnd., assignors to General Motors Corporation, Detroit,Mich, a corporation of Delaware Filed Nov. 25, 1957, Ser. No. 698,648 4Claims. (Cl. 103--37) This invention relates generally tofluid pumps andin its most. particular aspect concerns a wobble plate pump of. noveldesign andoperating characteristics. Insuch pumps the cylinders andpistons are so arranged that their axesare disposed about and parallelto the axis of the drive shaft, with the pistons in engagement with thewobble plate.

The invention has as a principal object to provide a pump of the typeindicated which is simple in construction, yet capable of providingfluid at the high pressure required, for example, in the operation of adump mechanism. or the like associated with a heavy oif-the-roadvehicle.

Another object is to provide a pump incorporating fluid actuated meanswhereby the effective displacement of the pump may be varied.

Still other objects and features of the invention will become apparentfrom the following description of a preferred embodiment thereof. Thedescription will proceed with reference to the accompanying drawingsillustrating such embodiment. In the drawings:

FIGURE 1 is a view taken online 1-1 of FIGURE 2, with certain partsshown broken away or in section;

FIGURE 2 is a section on the line 2-2 in FIGURE 1;

FIGURE 3 is a section on the line 3-3 in FIGURE 2;

FIGURE 4 is a section on the line 4--4 in FIGURE 2;

FIGURE 5 is a section on the li'neS-S in FIGURE 4;

FIGURE 6 is a section on the line 6--6 in FIGURE 1;

FIGURE 6a is a detail perspective view of a valve component; and

FIGURE 7 is a section on the line 77 in FIGURE 2.

Referring first to FIGURE 1, the numeral 10 denotes a drive shaft whichwill be seen as splined at 12, the splines enabling connection of theshaft to the output member of the power source contemplated.

A wobble member 14 shown as secured to the shaft 10 through a key 15turns in roller bearings '16 and carries a thrust plate 18 spaced fromthe wobble member by races 20 and 22 for rollers 24 and 26,respectively.

Inward of the wobble member 14 is a cylinder block maintained in itsnormal position shown by means of a coil spring '32 reacting against aplate 34 disposed between casing members 36 and 38. Plate 34 will beobserved as confining a roller bearing 40 for the drive shaft 10.

Within each of the cylinders 42 provided by the block 30 is a piston 44formed, as is conventional, with annular grooves 46 serving to entrapforeign matter which might interfere with proper operation of the pump.Each piston has a rounded nose portion 48 through which it engages thethrust plate 18.

Inaddition to the piston, each cylinder 42 partly confines a tubularmember 50 disposed in axial alignment with the piston. These tubularmembers provide fluid conduits 52 extending to a common dischargechamber 54 delineated by casing member 38 and plate 34. Mediate eachconduit 52 and the discharge chamber is a valve 56 shown as of the reedor flap type. As shown by FIGS. 6 and 6a the valves 56 are integral witha ring 59 which carries a lug 57, accommodated in a slot in the plate34, whereby at assembly the valves are located in proper orientationwith reference to the conduits 52.

The discharge chamber 54 opens to an outlet port 60.

2 Fluid entering the pump via inlet port 62 is received in an inletchamber 64 common to inlet ports 66 in the cylinder block 30.

Within each cylinder 42 a pair of springs 70, 72, housed by thecorresponding piston 44 and tubular member 50, seat against washers 74,76 respectively. At its end opposite the seat 74, spring 70 reactsagainst the head of the piston while spring 72 at its end opposite thewasher 76 reacts against an annular shoulder 80 formed by the reductionin the diameter of the tubular member 50.

With the arrangement as so far described and illustrated, it should beclear that on rotation of the drive shaft 10 and the wobble member 14pistons44, which are held in engagement with the thrust plate 18 by thesprings 70 and 72, are caused to reciprocate in the cylinders 42, thisaction being accompanied by entry of fluid into the cylinders via theinert port 66 and by the discharge of fluid through the conduits 52 pastthe reed valves 56 into the common discharge chamber 54. In FIGURE 1 theupper piston 44 is in discharge position while the lower piston has justcompleted its expansion or intake stroke.

To control the operation of the pump there is provided inter alia abridging sleeve 82 connecting with the discharge chamber 54 via apassage 84. The bore 86 of the sleeve opens to drilled passages 88 and'90 extending to a control valve 92 (FIG. 4) located in a bore 94 in thecasing member 36.

Valve 92 comprises lands 96 and 98 and has associated therewith a spring100 tending to maintain the valve in its shown position. As illustrated,spring 100 reacts against plate 34, the plate being recessed toaccommodate the end of the spring.

With the valve 92 in its normal position shown, discharge fluid enteringthe passage 88 is allowed to pass into a bore 102 confining a plunger104 comprising lands 106 and 108. These lands provide annular reactionsurfaces 110 and 112 and a third reaction surface 114. The rounded nose116 of the plunger 104 will be seen as bearing against a flange orprojection integral with the cylinder block 30, so that when thepressure in the bore 102 between the lands 106 and 108 reaches apredetermined value the plunger is displaced rightwardly to carry thecylinder block in that direction. Such displacement of the cylinderblock operates to delay the point in the pumping cycle of each piston atwhich compression may take place. In other words, the effective strokeof the pistons becomes shortened wtih corresponding reduction in theoutput from the cylinders,

When the discharge pressure becomes reduced to a value below thepredetermined value the cylinder block 30 is restored to its normalposition by the action of spring 32. On the other hand, should thedischarge pressure further increase plunger 104 becomes furtherdisplaced rightwardly to further shorten the effective stroke of thepistons 44 and, depending on the magnitude of the increased pressure,valve 92 may be shifted rightwardly against the resistance of spring 100to allow discharge fluid in the passage 90 to enter chamber 120 behindthe reaction surface 114. In this Way, the effective area of the plunger104, i.e. the area thereof responsive to the pressure of the dischargefluid, becomes the area of the surface 114 plus the area of the annularsurface 110 minus the area of the annular surface 112, whereas prior tothe displacement of the valve 92 the effective area of the plunger hadbeen the difference between the areas of annular surfaces 110 and 112.

Passage 122 through which discharge fluid enters chamher-120 leads to abore 125 (FIG. 3) located diametrically opposite the bore 102 andconfining a second plunger 104 which operates in all respects just asthe first de- 3 scribed plunger 104. As illustrated by FIGURE 7, thebore 125 between the lands 106 and 108 is at all times filled withdischarge fluid, such fluid, being supplied through a second bridgingsleeve 82. Bore 86 of the sleeve 82 (FIG. 7) will be seen ascommunicating with the bore 125 through a drill passage 130.

On the foregoing it should be understood that the two plungers 104 actsimultaneously and conjointly to displace the cylinder block 30 asgoverned by the discharge pressure, both plungers being under thecontrol of the valve 92 (FIGURES 4 and 5).

Only one stage of displacement of the control valve 92 has beendescribed, this being the condition when passage 90 becomes open topassage 122 leading to the chamber 120. Should the discharge pressurenow still further increase with the valve 92 in the indicated position,the valve will be shifted further rightwardly so that passage 88 and anannular channel 134 become interconnected allowing the discharge fluidto enter the intake chamber 64 via a short passage 136 extendingradially of the channel 134. Thus, valve 92 acts not only to regulate orcontrol the flow of discharge fluid to the chambers 120 but also as arelief valve.

What is claimed is:

1. In a pump comprising a housing, a drive shaft received within saidhousing, a wobble plate carried by said shaft, and a plurality ofradially arranged pistons disposed with their axes paralleling that ofsaid drive shaft and having portions in engagement at all times withsaid Wobble plate, the combination of a slidable member providingcylinders for said pistons, said member having therein a plurality ofinlet ports opening radially to the cylinders intermediate the endsthereof, means associated with said member tending normally to maintainit in a predetermined position, and a pair of plungers carried by saidhousing in diametrically opposed relation and abutting said member, saidplungers being subject to the pressure of the fluid discharged by thepump and sewing when such pressure reaches a predetermined value toaxially displace said member to change the positions of said portsrelative to said pistons thereby to reduce the output of the pump bydelaying the point in the pumping cycle of each cylinder at whichcompression may take place.

2. A pump as defined by claim 1 further comprising a valve carried insaid housing to control flow of discharge 4 fluid to said plungers, saidvalve serving additionally as a relief valve.

3. In a pump comprising a housing, a drive shaft received within saidhousing, a wobble plate carried by said shaft, and a plurality ofradially arranged pistons disposed with their axes paralleling that ofsaid drive shaft and having portions maintained in engagement with saidwobble plate, the combination of a partition within said housing at oneend thereof and serving with said housing to provide a dischargechamber, a slidable block providing cylinders for said pistons andhaving therein a plurality of inlet ports corresponding in number to thenumber of said cylinders, such ports opening radially to the cylindersintermediate the ends thereof, yieldable means reacting against saidhousing through said partition and urging said block in a directiontoward said wobble plate, means including a plurality of passages insaid partition for conveying fiuid from said cylinders to said dischargechamber, valve means in said passages, and a pair of plungers carried bysaid housing in diametrically opposed relation and abutting said block,said plungers being subject to the pressure of the fluid discharged bythe pump and serving when said pressure reaches a predetermined value toaxially displace said block to change the positions of said portsrelative to said pistons thereby to reduce the output of the pump bydelaying the point in the pumping cycle of each cylinder at whichcompression may take place.

4. A pump as defined by claim 3 further comprising a valve carried insaid housing to control flow of discharge fluid to said plungers, saidvalve serving additionally as a relief valve.

References Cited in the file of this patent UNITED STATES PATENTS2,483,705 Levetus et al. Oct. 4, 1949 2,678,607 Hufierd et al. May 18,1954 2,798,663 Chayne et al. July 9, 1957 FOREIGN PATENTS 402,603 GreatBritain Dec. 7, 1933 411,189 Italy July 18, 1945 411,190 Italy July 18,1945 484,114 Great Britain May 2, 1938 921,246 Germany Dec. 13, 19541,007,900 France Feb. 12, 1952

